I have Synergy setup between a Windows XP computer (Dual monitors) and a Linux computer (Dual Monitors). So it goes
[XP1] [XP2] [L1] [L2]. The XP computer is my server (running Synergy+).
Synergy seems to work fine going from XP1 XP2 and L1 but I can't get to L2. My cursor bumps up against the right edge of L1 and shakes a little but won't go over to L2. However if I plug a mouse directly up to the Linux box I can go between L1 and L2 just fine.